Motion measurement apparatus, motion measurement method, and motion measurement program

ABSTRACT

A motion measurement apparatus includes an inertial sensor and a host terminal. The inertial sensor measures a motion. The host terminal includes an input section and a control section. The input section is used to input an item identifier allocated to each motion of a user. The control section generates a control signal for controlling a sampling rate of the inertial sensor according to the item identifier which is input via the input section, and outputs the control signal to the inertial sensor.

TECHNICAL FIELD

The present invention relates to a motion measurement apparatus, a motion measurement method, and a motion measurement program.

BACKGROUND ART

PTL 1 discloses a swing analysis support apparatus. The swing analysis support apparatus includes a gyro sensor and an acceleration sensor attached to a golf club. The gyro sensor has three measurement axes which are orthogonal to each other, and detects an angular velocity about each measurement axis. The acceleration sensor has three measurement axes which are orthogonal to each other, and detects an acceleration along each measurement axis.

CITATION LIST Patent Literature

PTL 1: JP-A-2008-73210

SUMMARY OF INVENTION Technical Problem

In the related art, angular velocity and acceleration are uniformly detected for all swings. A calculation process is performed by using angular velocity or acceleration for each analysis item such as a head speed or a swing trajectory. Unnecessary data is also recorded depending on an analysis item. Therefore, there is the occurrence of power consumption during measurement or the occurrence of power consumption due to reading and writing for a memory, and thus there is a possibility of not being able to cope with a case where measurement is required for a longer period of time than detailed measurement, such as a case of a practice swing.

According to at least one aspect of the present invention, it is possible to provide a motion measurement apparatus, a motion measurement method, and a motion measurement program, capable of reducing power consumption more than in the related art.

Solution to Problem

(1) An aspect of the invention relates to a motion measurement apparatus including an inertial sensor that measures a motion; and a host terminal that includes an input section which is used to input an item identifier allocated to each motion of a user; and a control section that generates a control signal for controlling a sampling rate of the inertial sensor according to the item identifier which is input via the input section, and outputs the control signal to the inertial sensor.

The item identifier specifies an analysis item desired by a user. A calculation process may be determined for each analysis item. The calculation process may be performed according to a swing, and the analysis item desired by the user maybe presented to the user. In this case, a necessary output from the inertial sensor differs for each analysis item. A required minimum sampling rate of the inertial sensor differs for each analysis item. In the present motion measurement apparatus, a sufficient sampling rate can be selected for each analysis item, and, as a result, unnecessary measurement can be omitted as much as possible. In the above-described way, power consumption during measurement can be reduced.

(2) The inertial sensor may include a storage portion that stores an output from the inertial sensor; and a communication portion that transmits the output from the inertial sensor to an external device. If an information amount of measured values exceeds a communication capacity of the communication portion when a sampling rate is set, transmission and reception of the measured values may be hindered. Therefore, in this case, the measured values are temporarily stored in the storage portion, and the measured values are output from the communication portion at a favorable timing.

(3) In a case where the sampling rate is equal to or less than a transmission rate of the communication portion, the inertial sensor may transmit an output from the inertial sensor to the communication portion without using the storage portion. If an information amount of measured values is equal to or less than a communication capacity of the communication portion when a specific sampling rate is set, the measured values can be output from the communication portion in real time without using the storage portion. Therefore, reading and writing for the storage portion can be omitted. In the above-described way, power consumption during measurement is reduced.

(4) In a case where the sampling rate is more than the transmission rate of the communication portion, the inertial sensor may store an output from the inertial sensor in the storage portion, and transmit the output from the inertial sensor to the communication portion from the storage portion.

(5) The inertial sensor may include a plurality of sensors, and designate and control a specific sensor among the plurality of sensors on the basis of the control signal. As described above, a necessary output from the inertial sensor differs for each analysis item. A required minimum detection axis or physical quantity differs for each analysis item. In the present motion measurement apparatus, a detection axis or a physical quantity can be selected for each analysis item, and, as a result, it is possible to prevent unnecessary measurement from being performed or an unnecessary measured value from being output. In the above-described way, power consumption during measurement can be reduced.

(6) The control signal may cause the sampling rate of the designated specific sensor to be zero and thus the designated specific sensor to stop measurement. If measurement of a physical quantity in the sensor is stopped, power consumption during measurement is reduced.

(7) The control signal may be used to instruct an output from only the designated specific sensor to be transmitted. Although a physical quantity is measured by the sensor, if transmission of a measured value is stopped, power consumption during measurement is reduced.

(8) Another aspect of the invention relates to a motion measurement method including a procedure of inputting an item identifier allocated to each motion of a user; and a procedure of generating a control signal for controlling a sampling rate of an inertial sensor detecting a motion of the user according to the input item identifier, and outputting the control signal to the inertial sensor.

(9) Still another aspect of the invention relates to a motion measurement program causing a computer to execute: a procedure of inputting an item identifier allocated to each motion of a user; and a procedure of generating a control signal for controlling a sampling rate of an inertial sensor detecting a motion of the user according to the input item identifier, and outputting the control signal to the inertial sensor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram schematically illustrating a configuration of a swing measurement apparatus.

FIG. 2 is a block diagram schematically illustrating a configuration of the swing measurement apparatus.

FIG. 3 is a flowchart schematically illustrating a swing measurement method.

FIG. 4 is a plan view of a smart phone illustrating a specific example of a screen.

FIG. 5 is a plan view of the smart phone illustrating a specific example of a screen.

FIG. 6 is a plan view of the smart phone illustrating a specific example of a screen.

DESCRIPTION OF EMBODIMENT

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The present embodiment described below is not intended to improperly limit the content of the invention disclosed in the claims, and all constituent elements described in the present embodiment are not essential as solving means of the invention.

(1) Configuration of Swing Measurement Apparatus

As illustrated in FIG. 1, a swing measurement apparatus (motion measurement apparatus) 11 includes a sensor unit 12 and a host terminal 13. The sensor unit 12 is attached to, for example, a bat 14 in baseball or softball. The sensor unit 12 is attached to a grip end 14 a of the bat 14 via a mounting member 15. The sensor unit 12 maybe embedded in the mounting member 15. The mounting member 15 maybe made of, for example, a flexible material.

The host terminal 13 is formed of, for example, a smart phone 16. The smart phone 16 is provided with a display panel 17. A touch screen panel 18 overlaps a surface of the display panel 17. A user can check evaluation results of a swing group according to the display content on the display panel 17. Similarly, the user may input various instructions or conditions by using operating the touch screen panel 18. As the host terminal 13, a tablet PC terminal, a notebook PC terminal, or a desktop PC terminal may be used.

The sensor unit 12 is communicably connected to the smart phone 16, for example, in a wireless manner. For example, Bluetooth (registered trademark) may be used for wireless communication. In the above-described way, a detection signal from the sensor unit 12 is supplied to the smart phone 16.

As illustrated in FIG. 2, the sensor unit 12 includes an inertial sensor 21. Acceleration sensors 22 a, 22 b and 22 c and gyro sensors 23 a, 23 b and 23 c are incorporated into the inertial sensor 21. The acceleration sensors 22 a, 22 b and 22 c can respectively detect accelerations in three-axis directions which are orthogonal to each other. The gyro sensors 23 a, 23 b and 23 c can respectively detect angular velocities about three axes which are orthogonal to each other. The inertial sensor 21 outputs detection signals. The detection signals specify, for example, an x-axis direction acceleration, a y-axis direction acceleration, a z-axis direction acceleration, an angular velocity about the x axis, an angular velocity about the y axis, and an angular velocity about the z axis.

The sensor unit 12 includes a data processing section 24. The data processing section 24 is connected to the inertial sensor 21. Detection signals are supplied to the data processing section 24 from the inertial sensor 21 at a determined sampling rate. The detection signals are processed in the data processing section 24 so as to be converted into signals with a format suitable for communication. For example, the detection signals are converted into digital signals from analog signals.

The sensor unit 12 includes a transmission/reception section (communication section) 25. The transmission/reception section 25 is connected to the data processing section 24. Processed detection signals, that is, physical quantity data is supplied to the transmission/reception section 25 from the data processing section 24. The transmission/reception section 25 wirelessly outputs the physical quantity data according to a determined communication protocol.

The sensor unit 12 includes a memory (storage section) 26. The memory 26 is connected to the data processing section 24. The physical quantity data is supplied to the memory 26 from the data processing section 24. If an information amount of the physical quantity data is equal to or less than a communication capacity of the transmission/reception section 25, the data processing section 24 supplies the physical quantity data to the transmission/reception section 25 in real time. On the other hand, if an information amount of the physical quantity data is more than a communication capacity of the transmission/reception section 25, the data processing section 24 may accumulates the physical quantity data in the memory 26. In the above-described way, an output from the inertial sensor 21 is held in the memory 26.

The sensor unit 12 includes a sampling rate setting section 27. The sampling rate setting section 27 is connected to the inertial sensor 21 and the transmission/reception section 25. A control signal is supplied to the sampling rate setting section 27 from the transmission/reception section 25. The control signal specifies a flag value of a sampling rate. The sampling rate setting section 27 writes, for example, values of low-order 2 bits into 0xAA of a control register according to a flag value. Here, for example, if “0x02” is written into the control register, the inertial sensor 21 recognizes a sampling rate of 250 Hz, and if “0x01” is written into the control register, the inertial sensor 21 recognizes of a sampling rate of 1 kHz. A value of the control register and a sampling rate are correlated with each other on the inertial sensor 21 side.

The host terminal 13 includes a processing section 31. The processing section 31 is formed of, for example, a CPU. The processing section 31 is connected to a transmission/reception section 32. The transmission/reception section 32 may transmit and receive signals to and from the transmission/reception section 25 of the sensor unit 12 in a wireless manner. In the above-described way, the processing section 31 can process output signals from the sensor unit 12. The processing section 31 is connected to the display panel 17 and the touch screen panel 18. The processing section 31 may output processing results to the display panel 17, and may perform an operation determined by operating the touch screen panel 18.

The processing section 31 is connected to storage means such as a read only memory (ROM) 33, a random access memory (RAM) 34, and a nonvolatile memory 35. The processing section 31 uses the ROM 33, the RAM 34, and the nonvolatile memory 35. The ROM 33 stores a swing measurement software program and related data. The processing section 31 executes the swing measurement software program so as to realize a swing measurement method. For example, the RAM 34 temporarily holds the swing measurement software program when the swing measurement method is performed. The nonvolatile memory 35 stores a relatively small volume of program such as a basic input/output system (BIOS), and data.

The processing section 31 includes a data acquisition portion 36, a control portion 37, and a swing evaluation portion 38. The data acquisition portion 36 acquires physical quantity data of the sensor unit 12 which is received via the transmission/reception section 32. The data acquisition portion 36 stores the acquired physical quantity data in, for example, the RAM 34. The physical quantity data is stored in the RAM 34 in a time series.

The control portion 37 calculates swing analysis information on the basis of the physical quantity data acquired by the data acquisition portion 36. The swing analysis information includes an analysis value of each item for each swing. As items, there are a swing trajectory, the number of practice swings, a swing speed, a swing time, a grip rotation radius, an angle of the bat 14, a rotation angle of the bat 14, and the like. The control portion 37 derives a swing trajectory by using physical quantities such as an x-axis direction acceleration, a y-axis direction acceleration, a z-axis direction acceleration, an angular velocity about the x axis, an angular velocity about the y axis, and an angular velocity about the z axis, obtained at a sampling rate of 1 kHz. An attitude of the bat 14 is calculated, for example, every 1/1000 seconds on the basis of the physical quantities. On the other hand, the control portion 37 counts the number of practice swings by using an x-axis direction acceleration and a y-axis direction acceleration obtained at a sampling rate of 250 Hz. The control portion 37 detects a first swing and a last swing of the bat 14 when counting the number of practice swings. For example, states of a swing and “readiness in the box” are differentiated from each other by using a swing speed corresponding to 5% of an average swing speed as a threshold value. The swing speed specifies a head speed of the bat 14. The swing time specifies the elapsed time from the previous swing finishing to the present swing finishing. The grip rotation radius specifies a rotation radius of a trajectory of the grip end 14 a. An angle of the bat 14 specifies an inclined angle of the bat 14 with respect to a horizontal plane. The rotation angle of the bat 14 specifies a rotation angle of the bat 14 about a vertical axis. Any one of the above-described items may be calculated, an item group including several items may be calculated, and all of the items may be calculated. Such swing analysis information is specified on the basis of a trajectory or an attitude of the bat 14 during a swing. A signal for specifying an analysis value is output from the control portion 37 to the RAM 34. For example, the swing analysis information may be stored in the RAM 34 for each swing.

The control portion 37 is notified of an item identifier by the touch screen panel 18. In the notification, a signal for specifying an item identifier is input to the control portion 37. The item identifier specifies an item such as the “swing trajectory”, the “number of practice swings”, or the “swing speed”. A calculation process using physical quantity data from the sensor unit 12 is determined for each item identifier. For example, an item identifier specific to the “swing trajectory” is allocated to a calculation process thereof, an item identifier specific to the “number of practice swings” is allocated to a calculation process thereof, and an item identifier specific to the “swing speed” is allocated to a calculation process thereof. The control portion 37 generates a control signal for specifying a sampling rate of the inertial sensor 21 according to the type of item identifier. The control portion 37 may output the control signal to the inertial sensor 21.

The swing evaluation portion 38 evaluates swing analysis information for each item. The swing evaluation portion 38 specifies a target value for each item of the swing analysis information in the evaluation. The swing evaluation portion 38 acquires a signal for specifying a target value for an item. The target value may be stored in the RAM 34 in advance. Here, the user may designate and set the target value by operating the touch screen panel 18.

The swing evaluation portion 38 compares a target value with an analysis value for each swing. The swing evaluation portion 38 receives a signal for specifying an analysis value from the RAM 34 in the comparison. In the above-described way, it is evaluated whether or not each swing reaches a target value. The swing evaluation portion 38 specifies a proportion of swings reaching a target value in a swing group. A target achievement degree is evaluated according to the proportion.

(2) Operation of Swing Measurement Apparatus

In order to perform a practice swing of the bat 14, the user attaches the sensor unit 12 to the bat 14. The sensor unit 12 is fixed to the grip end 14 a of the bat 14. For example, the user operates the touch screen panel 18 according to the display content on the display panel 17, so as to activate the swing measurement software program. In the above-described way, a swing measurement method is performed.

As illustrated in FIG. 3, if the swing measurement software program is activated, the user is prompted to select an item in step S1. For example, as illustrated in FIG. 4, a “trajectory analysis mode” and a “practice swing mode” are displayed on a screen of the display panel 17. If the “practice swing mode” is selected, items to be used as indexes of the achievement degree may be further listed on the screen of the display panel 17. One or more items may be selected from among, for example, the swing speed, the swing time, the grip rotation radius, the angle of the bat 14, and the rotation angle of the bat 14. The touch screen panel 18 notifies the control portion 37 of an item identifier of a selected item in response to the user's operation.

The user sets a target value for each item as necessary. For example, a head speed such as xx km an hour may be set in the swing speed. The target value for the head speed provides a criterion on the strength of hitting a ball. The time may be set in the swing time in the unit of seconds. The target value for the swing time provides a criterion on a pace of a practice swing. A distance between the grip and the rotation center such as xx cm may be set in the grip rotation radius. The target value for the grip rotation radius provides a criterion on whether a swing is compact or large. An angle such as xx degrees may be set in the angle of the bat 14. The target value for the angle of the bat 14 provides a criterion on “standing of the head” or “lying of the head”. An angle such as xx degrees may be set in the rotation angle of the bat 14. The rotation angle of the bat 14 provides a criterion on a full swing or a half swing. For example, the user sets a target value by operating the touch screen panel 18. For example, as illustrated in FIG. 5, a blank for prompting the user to enter a target value is displayed on the display panel 17. Each target value may be stored in, for example, the RAM 28.

In step S2, the control portion 37 sorts item identifiers. If an item identifier is classified as a first class, the control portion 37 designates a high sampling rate in step S3. If the high sampling rate is designated instep S4, the control portion 37 generates a control signal with a sampling rate of 1 kHz. If an item identifier is classified as a second class, the control portion 37 designates a low sampling rate in step S5. If the low sampling rate is designated in step S4, the control portion 37 generates a control signal with a sampling rate of 250 Hz. A flag of “1” or “0” may be set in the control signal according to a sampling rate. The generated control signal is transmitted from the transmission/reception section 32. Here, it is assumed that the item “trajectory analysis mode” belongs to the first class, and the item “practice swing mode” and other items belong to the second class.

The sensor unit 12 receives the control signal via the transmission/reception section 25. The control signal is sent to the sampling rate setting section 27 from the transmission/reception section 25. The sampling rate setting section 27 writes a value into the control register of the inertial sensor 21 according to the flag “1” or “0” specified by the control signal. For example, if the “trajectory analysis mode” is selected in step S1, the flag “1” is set in the control signal, and “0x01” is written into the control register of the inertial sensor 21. A sampling rate of 1 kHz is set in the inertial sensor 21. For example, if the “practice swing mode” is selected in step S1, the flag “0” is set in the control signal, and “0x02” is written into the control register of the inertial sensor 21. A sampling rate of 250 Hz is set in the inertial sensor 21. If the sampling rate is set, the inertial sensor 21 starts measurement.

In a practice swing, readiness in the box and a swing are repeatedly performed. A detection signal is output from the inertial sensor 21 during a practice swing. If the user is in readiness, “readiness” is specified on the basis of the detection signal from the inertial sensor 21. Inmost cases, the “readiness” is recognized as a standing still state of the grip. If the user swings the bat 14, a change appears in the detection signal from the inertial sensor 21. For example, if the z axis direction matches of the shaft center of the bat 14, acceleration changes in an x-axis direction acceleration and a y-axis direction acceleration are specified in the detection signal. The data processing section 22 processes the detection signal. The processed detection signal is sent from the transmission/reception section 25 to the host terminal 13 as physical quantity data.

In step S6, the host terminal 13 receives the physical quantity data via the transmission/reception section 32. The data acquisition portion 36 acquires the physical quantity data of the sensor unit 12. The physical quantity data is stored in the RAM 28 in a time series.

The control portion 37 performs a calculation process according to a selected item in step S7. For example, if the “trajectory analysis mode” is selected, a swing trajectory is calculated for each swing on the basis of physical quantity data which is obtained at a sampling rate of 1 kHz. If the “practice swing mode” is selected, swing starting and swing finishing are calculated on the basis of an x-axis direction acceleration and a y-axis direction acceleration which are obtained at a sampling rate of 250 Hz. The number of swings is counted on the basis of swing starting and swing finishing. Similarly, if the “swing speed” is selected, a head speed is calculated on the basis of physical quantity data which is obtained at a sampling rate of 250 Hz. The trajectory, the number of swings, and the swing speed are stored in, for example, the RAM 34.

Here, it is determined whether or not the practice swing is completed in step S8. If the practice swing is completed, measurement in the inertial sensor 21 is finished. If the practice swing is not completed, measurement in the inertial sensor 21 is continuously performed. In addition, “readiness” is specified on the basis of the detection signal from the inertial sensor 21 again. The subsequent processes are repeatedly performed until the practice swing is completed. The user may finish the measurement in the inertial sensor 21 by operating the touch screen panel 18 even in the middle of the practice swing.

If the measurement in the inertial sensor 21 is finished, the swing evaluation portion 38 evaluates the swing. The evaluation may be started, for example, by the user operating the touch screen panel 18. The swing evaluation portion 38 acquires a target value and an analysis value from the RAM 28 for each swing. The swing evaluation portion 38 compares the target value with the analysis value. For example, if the “trajectory analysis mode” is selected, the swing evaluation portion 38 generates images of an ideal trajectory based on the target value and a trajectory of the user based on the analysis value in a determined display form. If the “practice swing mode” is selected, the swing evaluation portion 38 generates an image of the number of swings in a determined display form. In the “practice swing mode”, a target value and an analysis value may be compared with each other for each swing, and the swing evaluation portion 38 may count the number of swings in which an analysis value greater than a target value is obtained. If comparison for all swings is finished, a proportion of a greater analysis value to a total number of swings may be calculated. A target achievement degree for a swing group is evaluated according to the proportion. In the above-described way, the entire swing group may be evaluated. The evaluation result is displayed on, for example, the display panel 17 in step S9. An evaluation result of the “trajectory analysis mode” (FIG. 1) or the “practice swing mode” (FIG. 6) is presented to the user.

For example, if the swing speed is selected as an item, a proportion of swings corresponding to ball hitting showing the target strength or more is evaluated. If the swing time is selected as an item, it is evaluated how often the user rests during a practice swing. If the grip rotation radius is selected as an item, a proportion of achieving a compact swing is evaluated. If the angle of the bat 14 is selected as an item, a proportion of the head being down (lying) is evaluated. If the rotation angle of the bat 14 is selected, a proportion of full swings is evaluated. In the above-described way, the entire swing group is evaluated on the basis of a proportion of swings reaching a target value.

In the present embodiment, necessary physical quantity data differs for each item specified by an item identifier. A required minimum sampling rate of physical quantity data differs for each item. The swing measurement apparatus 11 can select a sufficient sampling rate for each item, and, as a result, unnecessary measurement is prevented as much as possible. In the above-described way, power consumption during measurement is reduced.

If a low sampling rate is set in the inertial sensor 21, an information amount of physical quantity data is equal to or less than a communication capacity of the transmission/reception section 25. Therefore, the physical quantity data is output from the transmission/reception section 25 in real time without using the memory 26. Reading and writing for the memory 26 are omitted. In the above-described way, power consumption during measurement is reduced. On the other hand, if a high sampling rate is set in the inertial sensor 21, an information amount of physical quantity data exceeds the communication capacity of the transmission/reception section 25. In this case, the physical quantity data is temporarily accumulated in the memory 26. If a swing is completed, the physical quantity data is output from the transmission/reception section 25. The physical quantity data is reliably sent to the host terminal 13.

In the present embodiment, necessary physical quantity data differs for each item. A required minimum detection axis or physical quantity differs for each item. For example, in the “practice swing mode”, as described above, an x-axis direction acceleration and a y-axis direction acceleration have only to be obtained. As a result, for example, if measurement of physical quantities is stopped in the acceleration sensor 22 c or the gyro sensors 23 a, 23 b and 23 c other than the acceleration sensors 22 a and 22 b measuring an x-axis direction acceleration and a y-axis direction acceleration, power consumption during measurement is reduced. Alternatively, even in a case where physical quantities are measured by the acceleration sensors 22 a, 22 b and 22 c and the gyro sensors 23 a, 23 b and 23 c, if only outputs from the acceleration sensors 22 a and 22 b are transmitted from the transmission/reception section 25, power consumption during measurement is reduced.

Although the present embodiment has been described as above in detail, it can be easily understood by a person skilled in the art that various modifications without substantially departing from the new matters and effects of the invention are possible. Therefore, these modifications are all included in the scope of the invention. For example, in the specification or the drawings, the terminologies which are mentioned at least once along with different terminologies which have broader meanings or the same meanings maybe replaced with the different terminologies in any location of the specification or the drawings. In addition, configurations, operations, and the like of the sensor unit 12, the host terminal 13, the mounting member 15, the smart phone 16, the display panel 17, the touch screen panel 18, and the like are also not limited to the above description of the present embodiment, and may have various modifications.

REFERENCE SIGNS LIST

11 motion measurement apparatus (swing measurement apparatus)

18 input section (touch screen panel)

21 inertial sensor

25 communication portion (section) (transmission/reception section)

26 storage portion (section) (memory)

32 control section 

1. A motion measurement apparatus comprising: an inertial sensor that measures a motion; and a host terminal that includes an input section which is used to input an item identifier allocated to motion of a user; and a control section that generates a control signal for controlling a sampling rate of the inertial sensor according to the item identifier which is input via the input section, and outputs the control signal to the inertial sensor.
 2. The motion measurement apparatus according to claim 1, wherein the inertial sensor includes a storage portion that stores an output from the inertial sensor; and a communication portion that transmits the output from the inertial sensor to an external device.
 3. The motion measurement apparatus according to claim 2, wherein, in a case where the sampling rate is equal to or less than a transmission rate of the communication portion, the inertial sensor transmits an output from the inertial sensor to the communication portion without using the storage portion.
 4. The motion measurement apparatus according to claim 2, wherein, in a case where the sampling rate is more than the transmission rate of the communication portion, the inertial sensor stores an output from the inertial sensor in the storage portion, and transmits the output from the inertial sensor to the communication portion from the storage portion.
 5. The motion measurement apparatus according to claim 1, wherein the inertial sensor includes a plurality of sensors, and designates and controls a specific sensor among the plurality of sensors on the basis of the control signal.
 6. The motion measurement apparatus according to claim 5, wherein the control signal causes the sampling rate of the designated specific sensor to be zero and thus the designated specific sensor to stop measurement.
 7. The motion measurement apparatus according to claim 5, wherein the control signal is used to instruct an output from only the designated specific sensor to be transmitted.
 8. A sensor unit comprising: a storage section that stores an output from the inertial sensor; and a communication section that transmits the output from the inertial sensor to an external device, wherein, in a case where the sampling rate is equal to or less than a transmission rate of the communication section, the inertial sensor transmits an output from the inertial sensor to the communication section without using the storage section.
 9. The sensor unit according to claim 8, wherein, in a case where the sampling rate is more than the transmission rate of the communication section, the inertial sensor stores an output from the inertial sensor in the storage section, and transmits the output from the inertial sensor to the communication section from the storage section.
 10. The sensor unit according to claim 8, wherein the inertial sensor includes a plurality of sensors, and the sensor unit designates a specific sensor among the plurality of sensors and controls a sampling rate on the basis of a control signal from an external device.
 11. The sensor unit according to claim 10, wherein the sampling rate of the designated specific sensor is caused to be zero, and thus the designated specific sensor stops measurement, on the basis of the control signal.
 12. The sensor unit according to claim 10, wherein an output from only the designated specific sensor is transmitted on the basis of the control signal.
 13. A host terminal comprising: an input section which is used to input an item identifier allocated to motion of a user; and a control section that generates a control signal for controlling a sampling rate of an inertial sensor detecting a motion according to the item identifier which is input via the input section, and outputs the control signal to the inertial sensor.
 14. The host terminal according to claim 13, wherein the inertial sensor includes a plurality of sensors, and designates and controls a specific sensor among the plurality of sensors on the basis of the control signal.
 15. The host terminal according to claim 14, wherein the control signal causes the sampling rate of the designated specific sensor to be zero and thus the designated specific sensor to stop measurement.
 16. The host terminal according to claim 14, wherein the control signal is used to instruct an output from only the designated specific sensor to be transmitted.
 17. A motion measurement method comprising: a procedure of inputting an item identifier allocated to motion of a user; and a procedure of generating a control signal for controlling a sampling rate of an inertial sensor detecting a motion of the user according to the input item identifier, and outputting the control signal to the inertial sensor. 